Resumo

Plasma position measurements of frequency modulation continuous wave reflectometry are analyzed in ASDEX Upgrade ELMy H-mode regimes [International Thermonuclear Energy Reactor (ITER) reference scenario], to assess the viability of using reflectometry for position and shape control purposes in ITER. Plasma separatrix position is estimated both at the low and high field sides of the tokamak. A scaling factor applied to the linear average density (an ITER online measurement) is used to estimate the separatrix density, whose position is then tracked using reflectometry profile measurements. Edge localized mode (ELM) activity effects are overcome by disregarding measurements performed during the onset and magnetohydrodynamic phases of the ELMs. Position data is compared, with data derived from the magnetics and its quality is assessed using one dimensional full-wave numerical simulations, taking into account the influence of the nonprobed edge plasma region (O-mode operation) and of the plasma turbulence. Results indicate that selecting an adequate scaling to the linear average density leads to a good estimate of the separatrix position, even when the pedestal is out of the measuring range, which will be the case of ITER position reflectometer.